Method of forming disc brake piston



Nov. 20, 1962 s. SCHNELL 3,064,346

METHOD OF FORMING DISC BRAKE PISTON Original Filed July 15, 1957INVENTOR. STEVE SCHNELL ATTORNEYS United States Patent METHGD F FQRMENGDlSC B PlSTON Steve Schnell, Berkeley, Mo., assignor to Wagner ElectricCorporation, St. Louis, Mo., a corporation of Delaware Originalapplication duly 15, 1957, Ser. No. 671,953, new

Patent No. 2,964,136, dated Dec. 13, 1950. Divided and this applicationDec. 23, 1959, Ser. No. 361,648

5 Claims. (Cl. 29-493) This invention relates generally to the art ofassembling annular parts and in particular to a method of forming anannular piston assembly for a disc brai'e.

In the past, parts forming annular piston assemblies for disc brakeshave been provided with radially extending flanges which have been heldin surface contact and secured by rivets, brazing or the like. Otherprior art methods of assembling annular piston assembly parts haverequired precise machining of parts or the use of seals in finalassembly in order to assure fluid tight chambers and secure assembly.

The principal object of the instant invention is to provide an improvedmethod of assembling wnular disc brake parts which obviates thedisadvantages known heretofore and provides a simple eflicient method ofproducing uniform brake assemblies.

These and other objects and advantages will become apparent hereinafter.

Briefly, the present invention comprises the method of pre-assemblingtelescopically arranged first and second piston forming annular members,applying opposing forces maintaining the first and second members intelescopic relationship, applying a compressive force holding the sidewalls of the members in surface abutment, and providing means securingthe side walls of the members together in sealed relationship. Theinvention further consists in the method of assembling the parts of thearticle, as set forth in the following description.

In the accompanying drawing which forms a part of the present disclosureand wherein like numerals refer to like parts wherever they occur, thesingle FIGURE is a sectional view showing a typical piston assembly incross section during manufacture to illustrate the present method.

This application is a division of co-pending patent application SerialNo. 671,953, filed July 15, 1957, now Patent No. 2,964,136, entitledAnnular Piston Assembly for a Disc Brake.

A typical annular piston assembly made according to the present methodcomprises a piston member 11 that is U-shaped or channel-shaped incross-section and includes axially-extending radially-spaced side walls12 and 13 interconnected by a base wall 14, which includes annularperipheral ribs 15 and 16 defining a recess 17 therebetween. The freeends of the piston side walls 12 and 13 are provided with a plurality ofspaced cross-passages or slots 18, and peripheral expansion grooves 19and 29 are formed in the remote or outer surfaces of the side walls 12and 13 in communication with the cross-passages 18.

The piston assembly 13 also comprises a friction plate 21 which ispreferably formed of a relatively thin, annular, metal plate having highheat conductivity properties. The plate 21 includes a base wall 22 withradially-spaced axial flanges or side walls 23 and 24, the base wall 22having a plurality of annular cooling fins 25 or the like on the innersurface thereof. The friction plate 21 is secured to the open end of thepiston 11 opposite the piston base wall 14 to define a closed chamber 26therebetween, the free ends of the piston side walls 12 and 13 abuttingthe interior surface of the plate base wall 22 adjacent to the plateflanges 23 and 24. The free ends of the plate flanges 23 and 24 extendaxially past the expansion grooves 19 and 20 and are in telescopicsurface abutment with the remote or outer surfaces of the piston sidewalls 12 and 13. The piston 11 and the friction plate 21 are secured infixed relationship according to the present method by annular filletwelds or brazing 27. It is apparent that substantially the entireinterior surface of the friction plate 21 is exposed to the chamber 26either directly or through the cross-passages 18 and the peripheralexpansion grooves 13 and 20.

The inner or adjacent surfaces of the piston side Walls 12 and 13 areprovided with aligned circumferential grooves 28 and 29 in which a pairof baflles 30 and 31 are secured in circumferential alignment, thebaffles 3i and 31 dividing the chamber 26 into a circulatory chamber 32defined between the baffles and the friction plate 21 and a staticchamber 33 defined between the baffles and the piston base wall 14.Adjacent end portions of each of the baffles 31) and 31 are spaced apartin alignment with an inlet and an outlet (not shown) to the chamber 26for the admission and circulation ofcooling fluid during actualoperation of the piston device 10 in a brake system. It is also apparentthat if unusually high heat is required to secure the parts by brazingor the like, cooling fluid may be circulated through the circulationchamber 26 during assembly of the parts by this method to dissipate thisheat.

The piston assembly 10 may also include other features important to itsfunction in a brake system, but forming no part of the present method.

The present method of assembling the friction plate 21 and the pistonmember 11 to form the piston assembly 10 includes the pre-assembly stepsof positioning the bafile plates 30 and 31 in the circumferentialgrooves 28 and 29 of the adjacent piston side walls 12 and 13, andtelescoping the flanges 23 and 2.4 of the friction plate 21 with theremote surfaces of the piston side walls 12 and 13. Thus, the frictionplate 21 is in pro-assembled position with the piston member 11 and thefree ends of the piston side walls 12 and 13 are abutting the frictionplate base wall 22.

An annular expansion ring 34 is provided for pressing the inner flange24 of the friction plate 21 against the inner wall 13 of the pistonmember 11. The expansion ring 34 is compressed slightly and positionedsubstantial ly in radial alignment with the baffle members 30 and 31 andpermitted to expand to press into position against the flange 24 of'thefriction plate 21 thereby effecting a light press fit between theabutting surfaces of the piston side wall 13 and the friction plateflange 24. An annular compression ring 35 is positioned about the outersurface of the friction plate flange 23 to cause a light press fitbetween this flange and the piston side wall 12. When thus arranged, therings 34 and 35 are aligned with the free end margins of the frictionplate flanges 23 and 24 and form expansion and compression means to holdthe abutting portions of the friction plate flanges in a sealedcondition with the side walls 12 and 13 of the piston member 11.

The expansion and compression rings 34 and 35 are preferably continuousfor exerting even pressures on all portions of the telescoped pistonassembly parts. For instance, the rings 34 and 35 may be a continuoushelical plate ring or it may be desired to merely use split rings ofpredetermined force and size. It is apparent that a split ring may becompressed or expanded from its natural diameter and, thus, may be usedeither as an expansion ring or as a compression ring for different sizedpiston assemblies.

Annular clamping plates or blocks 36 and 3 7 are positioned in abuttingrelationship with the base Walls 14 and 22 of the piston member 11 andfriction plate 21 and the clamping plates 36 and 37 are held in positionby a plurality of C-clamps 33 or the like. Accordingly,

the friction plate 21 and piston member 11 are held in assembledrelationship by the axial pressures exerted thereagainst by the clampingplates 36 and 37 to prevent warpage of the piston assembly duringwelding or brazing.

A brazing material, such as silver solder or the like, is positioned atthe free ends of the friction plate flanges 23 and 24 and against thepiston side walls 12 and 13 to form annular rings of materialtherebetween. The brazing material is then heated to liquefyingtemperature and then'cooled to form the continuous fillet welds 27permanently securing the friction plate 21 and piston member 11together.

It is now apparent that the clamping plates 36 and 37 exert axialpressures maintaining the piston assembly 13 in assembled non-warpingcondition, and that the annular expansion and compression rings 34 and35 exert radial pressures maintaining the side walls of the pistonmember and friction plate in abutting sealed condition whereby thebrazingmaterial is prevented from entering and blockingthe peripheralexpansion grooves 45 and 46 between the respective side walls of thepiston member 31 and friction plate 47.

The present disclosure is intended to cover all changes andmodifications of the present invention which will be apparent tooneskilled in the art and which do not constitute departures from thespirit and scope thereof, the present invention being limited only bythe claims which follow. 7

What I claim is: t

l. 'The method of assembling an annular friction plate member havingradially-spaced axial side walls and a radial base wall and a pistonmember having radiallyspaced axial side walls and a radial base wall toform a piston assembly, the methodcomprising the steps of arranging theside walls' of said members in telescoping pairs of adjacent walls,pressing substantially continuous means into position with each pair ofwalls to press the adjacent walls in each pair into sealed condition,apply ing clamping means across the base walls of said members, andsealing the members togetherat the external juncture of each pair ofwalls.

2. The method of assembling an annular friction plate member havingradially-spaced axial side walls and a radial base wall and an annularpiston member having radially-spaced axial side walls and a radial basewall to form an annular piston assembly for a disc brake, the methodcomprising the steps of arranging the side walls of said members intelescoping pairs of adjacent walls in surface contact, pressingsubstantially continuous means 'into position with each pair of walls topress the contacting portions of the adjacent walls in each pair intosealed condition, applying clamping means across the base walls of saidmembers, and brazing the members together at the external juncture ofeach pair of walls.

3. The method of assembling an annular friction plate havingradially-spaced axial side flanges and a radial base wall and a pistonmember having radially-spaced axial side walls and a radial base wall toform a piston assembly for a disc brake, the method comprising thesteps. of pre-assembling the friction plate and piston member includingpositioning a baffle between the adjacent surfaces of the side walls ofthe piston member and telescoping the side walls within the side flangesof the friction plate to form surface abutments therebetween, pressing asubstantially continuous annular member into expanding abutting positionagainst one of the side flanges to press it into sealed condition withthe abutting side Wall, pressing another substantially continuousannular member into compressing abutting position with the other sideflange to press it into sealed conclamping block in abutting positionwith each of the base walls, applying clamping pressures to the clampingblocks to hold the friction plate and piston member in fixed assembledrelationship, and sealingly securing the friction plate and pistonmember together at the external juncture of the side flanges and sidewalls thereof.

4. The method of assembling an annular friction plate havingradially-spaced axial side flanges and .a radial base wall and a pistonmember having radially-spaced axial side walls and a radial base wall toform a piston assembly for a disc brake, the method comprising the stepsof pre-assembling the friction plate and piston member includingpositioning a baflle radially between the adjacent surfaces of'the sidewalls of the piston member and telescoping the side walls within theside flanges of the friction plate to form surface abutmentstherebetween substantially in the radial plane of said baffle, pressingan annular ring into expanding abutting position against one of the sideflanges to press it into sealed condition with the abutting side wall,pressing another annular ring into compressing abutting position withthe other side flange to press it into sealed condition with theabutting side wall, positioning an annular clamping block in abuttingposition with each of thebasc walls, applying clamping pressures to theclamping blocks to hold the friction plate and piston member in fixedassembled relationship, and brazing the friction plate and piston membertogether at the external juncture of the side flanges and side wallsthereof.

5. The method of assembling an annular friction plate havingaxially-extending radially-spaced side flanges and a radial base walland an annular piston member having axially-extending radially-spacedside walls and a radial base wall .to form a piston assembly, the methodcom-'- prising the steps, of'pre-asssembling the friction plate andpiston member including positioning a baffle radially between theadjacent surfaces of the piston member side walls and fitting the pistonmember side walls into the friction plate side flanges to formcontinuous surface abutments therebetween, pressing an annular internalexpansion ring into abutting position with the radially' inner frictionplate side flange to press the flange outwardly into sealed conditionwith the piston member side wall abutment therewith, pressing an annularexternal compression ring into abutting circumscribing' position withthe radially outer friction plate side flange to press the flangeinwardly into sealed condition with the piston member side wall inabutment therewith whereby the dition with the abutting side wall,positioning an annular bafiie holds the piston member side Walls inradially spaced relation and the rings exert opposing circumferentialforces-against the side walls and flanges of the'piston member andfriction plate, positioning annular clamping plates in abutting positionwith the base walls of the piston member and friction plate, applyingclamping means across the clamping plates to exert opposing axial forcesholding the piston member and friction plate in fixed assembledrelationship, positioning brazing material circumferentially at thejuncture of the side walls and flanges of the piston member and frictionplate, and heating the brazing material to a liquifying temperature andsubsequently cooling the brazing material to form continuous annularwelds securing the piston member and friction plate together.

References Cited in the file of this patent UNITED STATES PATENTSDaugherty Aug. 14, 1956 UNITED STATES PATENT OFFICE CERTIFTCATE @l@(TRRECTIQN Patent N00 3,064,346 November 20, 1962 Steve Schnell ifiedthat error appears in the above numbered pat- It is hereby cert ersPatent should vread as ent requiring correction and that the said Lettcorrected below.

Column 1 line 43 for "patent" read parent column 2, line l, after"fixed" insert telescopic column 4, line 44 after well insert in Signedand sealed this 21st, day of May 1963 (SEAL) Attest:

ERNEST w. SWIDEE DAVID LADD Commissioner of Patents Attesting Officer

